In a known system, a mobile communication terminal and a display apparatus are communicably connected to each other so that an operation on content of the mobile communication terminal is inputtable from both of the mobile communication terminal and the display apparatus. For example, JP 2010-130670A1 discloses that a display apparatus mounted to a vehicle acquires information from a mobile communication terminal connected to the display apparatus and displays the acquired information on a display.
In this relation, the inventor of the present application has found out the following. When the operation on the content is inputtable from both of the mobile communication terminal and the display apparatus, different users can operate the content by using the mobile communication terminal and the display apparatus. Since the operation with use of the mobile communication terminal or the display apparatus leads to the same change in the display of the two apparatuses, it becomes difficult to grasp which of the two apparatuses has been used to input the operation.